Relief device for power presses



May 26, 1953 P. G. PATER RELIEF DEVICE FOR POWER PRESSES 2 Sheets-Sheet l e D d e l 1 F INVENTOR. Paal 6. Pater P. G. PATER RELIEF DEVICE FOR POWER PRESSES May 26, 1953 2 Sheets-Sheet 2 Filed Dec. 24, 1951 1 N VEN TOR. Paul G Fal er Patented May 26, 1953 RELIEF DEVICE FOR/ POWER PRESSES Paul G. Pater, Hamilton, Ohio, assignor to Columbia Machinery and Engineering Corporation, Hamilton, Ohio Application December 24, 1951, Serial No. 263,080

6 Claims. 1

This invention relates generally to metal working power presses and is particularly directed to an improved relief device for power press brakes, that is connected between the ram and the driven eccentric of the press brake for the purpose of unlocking the parts when they become frozen having one or more eccentrics, and pitmans connecting the eccentrics to the ram. In such presses it is necessary to close the dies during the metal forming stroke with the metal to be formed interposed between them. If an abnormally thick piece of metal, or more than one thickness of a metal upon which the machine is set to operate, is accidentally inserted between the dies the normal throws of the movable die, the eccentrics and pitmans are restricted to such an extent that the parts cannot be driven through their operative dead center positions, with the result that said press parts stop on dead center positions and cause looking or freezing of the parts in said positions. The locked or frozen' condition of the press would then be relieved by the long and tedious method of burning out one of the press dies.

The present invention provides a press wherein an inconspicuous, and extremely simplified relief device is interposed between the ram and the driven eccentric of the press, and is disposed in an accessible position for effective operation,

in the event the press parts become locked or jammed for the reasons set forth heretofore.

Another object of the invention is to provide an improved device that relieves abnormal pressure between the jammed parts of a locked press, thus permitting movement of said parts from their locked, dead center positions by the normal drive means of the press.

A further object of the invention is to provide a relief device for power presses having the foregoing characteristics which is so located and associated with the ram and the pitman of the press as not to interfere in any way with the normal operation of press brakes equipped with the relief device.

With these and other objects in view the invention consists of the features of construction,

.combination and arrangement ofv parts, hereinafter fully described and claimed, reference being had to the accompanying drawings, in which:

Fi 1 is a front elevational view of an exemplary power press brake illustrative of my present invention.

Fig. 2 is an enlarged section taken on line 2-2 of Fig. 1.

Fig. 3 is a fragmental, elevational view of the pitman and ram connector illustrated in Fig. 2.

Fig. 4 is a section taken on line 44 of Fig. 3.

Fig. 5 is a section taken on line 55 of Fig. 3.

Fig. 6 is a perspective view of the wedge for my relief device.

In the drawings the numeral indicates a power press brake having a pair of opposed heavy metal side plates II and [2, connected at their lower portions by a front plate 13 and at their upper ends by two beams I l-14 to form a rigid press frame. The upper end of the front plate carries a bed for supporting a suitable stationary die member l6, whilst the forward edges of the side plates II and I2, above the bed, are provided with suitable slides I! and [8 respectively for guiding a ram I9 for vertical reciprocating movement toward and away from the bed. The lower edge of the ram is provided with a mounting means for securing a movable die member 2| thereto. As best shown in Fig. 2 the press may be set up to bend angle irons 22 from flat strip metal by mounting a female die upon the bed 15 and a cooperative male die member on the ram iii.

A driving shaft 23 is mounted in journal bearings 24 and 25 carried by the upper ends of the side plates II and I2 respectively, said shaft having fixed to one end a toothed, bull wheel 26 which is power driven in the usual manner by an electric motor 21 through reduction gearing, generally illustrated by the reference numeral 28. Two pitmans 29 and 30 each have a machined ,orifice 3! (Fig. 2) to fit over its respective eccentric 32 on the shaft 23. The lower ends of the pitmans are secured to the ram l9 by con- The shaft is supported in the pitman by a nut 39 which is rotated by a worm 40, said shaft being precluded from rotation by, a pint! anchored in a socket cap 42, and extending therefrom into the ball. To adjust the vertical position of the ram relative to the bed, the nuts of both connectors 33 and 34 are preferably rotated in unison by a cross shaft 43 which has the operating worms for the connectors fixed to its ends, said shaft being selectively connected with a motor (not shown) by means of a clutch device 44 controlled by a manually operated lever 45 (Fig. 1).

With particular reference to Figs. 3 and 4 of the drawings my improved relief device comprises a substantially rectangular notch 46 formed in the upper edge ll of the ram to receive the connector block 38. The notch forms a planar bottom Wall 48 and two preferably vertical side walls 49 and 50 in the ram body, the upper ends of the side walls terminating in inwardly extending shoulders 51 and 52 respectively. The

body of the connector block 38 is slidably posiportions of the front face of the ram surrounding the notch. The connector body has a planar bottom wall 56 spaced from the bottom wall 48 of the notch i6 and inclined downwardly and rearwardly with respect to the front face of the ram. A single wedge 51 is interposed between the bo m wal s of h conne t rand, the tem. a flat wall 58 of the wedge being in face-to-face contact with the bottom wall 48 in the notch, whilst an inclined wedge wall 59 is in contact with the bottom 56 ofthe connector body.

The wedge has a lateral dimension substantially the thickness of the ram and in its normal operative position is located upon the ram within the vertical extensions of the front and rear faces of the ram, the wedge being held against forward displacement by a set of set screws 80. It will be noted that in said wedge position the block 38 is held against the shoulders 5| and 52 formed on the ram. The connector body is secured in said position against lateral displacement by set screws 6| which pass through vertically extending slots 63. and 84 formed in the flanges 53 and respectively, said set screws cooperating with threaded bores formed in the ram body. Spacing washers 65 surround the set screws 6| and are interposed between the vertical flanges 53 and 54 and the ram bodyto maintain the flanges in spaced relationship with respect to the front face of the ram. As will be noted in Fig. 5 the set of set screws are threaded in the flange 55 and have their lead ends bearing against the major face 66 of the wedge. A set of pull bolts 67 pass through spaced bores formed in the bottom flange 55 of the connector body and cooperate with threaded bores 68 formed in the major face of the wedge, said set of pull bolts 61 preferably alternating along said flange with the set of set screws 60.

The wedge 51 is made of hard metal and the tangent of the angle of inclination of the ram and connector contacting surfaces 58 and 58 of the wedge is somewhat greater than the coefficient of friction of the hard metal wedge and the material of the ram, so as to insure horizontal movement of the wedge by the pull bolts 51 when abnormal locking pressures occur in the press parts. On the other hand the tangent of the wedge angle should not be so great as to place undue strain on the wedge set screws 60 during normal operation of the press. It is thought that the wedge angle should be approximately 15 to achieve the best results. It may be desirable in some press constructions to case harden the contacting surfaces of the wedge, and the wedge contacting surfaces of the connector and the ram, and in some instances apply lubricants to these surfaces to reduce the force of friction between said surfaces.

In normal operative position the connector is in the condition illustrated throughout the drawings wherein the wedge 51 is within the vertical lines of the ram [9 with the set of set screws 60 tightened firmly against the major face 86 of the wedge 5,! to position the connector 38 in the notch 46 so that it bears against the shoulders 5| and 52 formed on the ram. The connector is secured in this position in the notch by tightening up on the set screws 6| to preclude the lateral displacement of the connector from the notch in the ram. The pull bolts 61 are threaded in their respective bores with sufficient pressure to prevent their being backed out by press vibrations. or the like. When the press parts become accidentally locked in frozen, dead center positions my relief device is made effective by loosening set screws 5! and retracting the set of set screws 60. Then by successively turning up on the set f p ll ol 61. the wedge will b pulled forward from between the surfaces 48 and 5.6 on the ram and onn ctor re pec ively t lessen the distance between the die 2.! and; the. center of. the eccentric 32 and thereby relieve the lock.- ing pressure and permit the press parts to be moved under normal press pow r to an inoperative position. To. recapture the established setting of the press parts it. is. only necessary to turn the set of set screws 60 and return the wedge to its operative position illustrated inv the drawings where the connector will again contact. the limiting shoulders 5| and 52 on the. ram.

What is. claimed is:

1. In a relief device for power presses the combination of a reciprocated ram having a notch formed in an edge thereof, a power driven pitman, a connector secured to the pitman and mounted in the notch for limited movement in the direction of ram reciprocation and having a flange overlapping the marginal edge portions of the ram around the notch, a single wedge interposed between the connector and the ram and. in face-to-face engagement with the adjacent faces of the connector and the ram, releasable means permitting relative adjustment of the connector and the ram in the direction of reciprocation of the ram and operative to secure the connector to the ram, a set of laterally effective pull bolts passing through the flange and threaded in threaded bores formedin a side of the wedge, and a set of set screws threaded in the flange and bearing at their lead ends against said side of the wedge.

2. In a relief device for power presses according to claim 1 characterized by the factthat the notch in the ram has a stop means formed at its mouth against which the connector is engaged when the set screwsare adjusted to maintain the wedge in operative position.

3. In a relief device for power presses the combination of a vertically reciprocated ram having a notch formed in its upper edge, a power driven pitman located above the ram, a connectorsecured to the pitman and mounted in the notch for limited vertical movement with respect to the ram, said connector having a pair of side flanges and a bottom flange overlapping the marginal edge portion of the ram around the notch, releasable means permitting relative adjustment of the connector and the ram in the direction of reciprocation of the ram and operative to secure each side flange of the connector to the ram, a single wedge interposed between, and in face-to-face contact with the relatively inclined bottom faces of the connector and of the notch, a set of pull bolts passing through bores formed through the bottom flange of the connector and cooperating with threaded bores formed in the adjacent major side of the wedge, and a set of screws threaded in said bottom flange and bearing at their ends against the said side of the wedge.

4. In a relief device for power presses according to claim 3 characterized by the fact that the releasable means for securing the side flanges of the connector to the ram consists of an elongated slot formed in each flange for receiving set screws threaded in the ram.

5. In a relief device for power presses the combination of a vertically reciprocated ram formed with a notch in its upper edge, said notch having a planar bottom Wall normal to the front face of the ram, a power driven pitman located above the ram, a ball and socket connector fixed to the lower end of the pitman and mounted for limited vertical movement in the notch, said connector having a pair of side flanges and a bottom flange overlapping the marginal edge portions of the front face of the ram surrounding the notch,

and spaced laterally therefrom, said connector having a planar bottom wall spaced from the planar bottom Wall of the notch and inclined downwardly and rearwardly with respect to the front face of the ram, a single wedge interposed between, and in face-to-face contact with the planar bottom walls of the connector and of the ram, said wedge having a lateral dimension substantially the thickness of the ram, vertically elongated slots formed in the side flanges, a set screw extending through each slot and threaded in the ram, spacing washers surrounding the set screws and positioned between the flanges and the front face of the ram, a set of pull bolts passing through spaced bores formed in the bottom flange of the connector and threaded in threaded bores formed in the major face of the wedge, and a set of set screws alternately positioned along the flange with respect to the pull bolts and cooperating with threaded bores formed in said bottom flange with their lead ends bearing against the major face of the wedge.

6. In a power press the combination with a bed having a fixed die member mounted thereon, a reciprocated ram carrying a die member for movement toward and away from the fixed die member, power driven eccentric shaft, and a pitman connecting the eccentric shaft with the ram the combination of, a substantially rectangular notch formed in an edge of the ram, a ball and socket connector mounted in the notch for limited movement in the direction of ram reciprocation, means for securing the connector to the pitman, said connector having a flange overlapping the marginal edge portions of the ram around the notch, a single wedge interposed between the connector and the ram and in faceto-face contact with the adjacent, relatively inclined faces of the connector and the ram, means permitting relative adjustment of the connector and the ram in the direction of reciprocation of the ram and operative to connect the flange to the ram in adjusted position, a set of laterally effective pull bolts passing through the flange and threaded in a side of the wedge, and a second set of set screws threaded in the flange and bearing at their lead ends against said side of the wedge.

PAUL G. PATER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,038,795 Klocke Apr. 28, 1936 2,136,586 Long Nov. 15, 1938 2,175,742 Clouse Oct. 10, 1939 

